4) -arcsin (-1) - 1/π arccos √2/2.

Математика. $$-arcsin(-1) - \frac{1}{\pi} \cdot arccos(\frac{\sqrt{2}}{2}) = -(-\frac{\pi}{2}) - \frac{1}{\pi} \cdot \frac{\pi}{4} = \frac{\pi}{2} - \frac{1}{4} = \frac{2\pi - 1}{4}$$ Ответ: $$\frac{2\pi - 1}{4}$$